Whiskers, or “vibrissae” to use their technical name, are no normal type of hair. They are highly sensitive navigation and sensory tools supplying your dog with important information about their environment. They are distinctly different to the hair found on their bodies - more rigid, coarse and more deeply embedded in the skin, almost comparable to antennae in other creatures.
Their primary function is to assist their vision, particularly in the dark, by providing them with extra information that their eyes might be missing. The whiskers are full of nerves which send information to the brain, such as a warning if something is close to the face, helping them to navigate or avoid harmful objects or encounters. Though the whisker itself cannot “feel”, the nerve endings concentrated at the base react when something touches the whisker, causing it to vibrate.
By using their whiskers, dogs can detect an object's shape, roughness, size and speed, including those blocked from view by their noses. It is also thought that a dog might instinctively flare their whiskers if feeling threatened, using them as a communication tool to relay their feelings.
They can even detect tiny changes in air currents, meaning that thanks to their whiskers, dogs don’t even need to touch something in order to know it's there. Changes in the air stirred up around them as they approach something will tell them that an object or obstacle is coming up, even if they can’t see it.
In terms of care for your dog’s whiskers, it’s best to leave them alone. It can be disorienting for your dog to lose them and can compromise their ability to “feel” with their faces, causing them to be uncertain in low light as they can’t fully interpret their surroundings. While they do grow back if trimmed, they will shed and replenish them naturally on their own - favour their purpose over their presentation!
Read more in the following articles:
Why Do Dogs Have Whiskers? Psychology Today
What's the Deal with...Whiskers?
Why Do Dogs Have Whiskers? Pet Md